Audion tube tester



July 16, 1935.

TRIPLETT AUDION. TUBE TESTER Original Filed Jan. 11, 1952 2 Sheets-Sheet 2 RAv 1.. TRIPLETT,

mbam 5mm all t/nu;

Patented July 16, 1935.

' A gown UNITED STATES PATENT OFFICE a 2,007,989

' AUDION TUBE TESTER Ray L; Triplett, Bluffton; Ohio Original application Januarytll, 1932, Serial No.

585,937. Divided and this application March 13, 1933, Serial No. 660,569. I v 'j f1, 8 Claims. (omen-2n This invention relates to a method of and apparatus ,for testing vacuum tubes, and particularly to methods andapparatus in which an alternating current source may. be employed'to, energize all of the circuits of the tube.

Ill-

tron flow is increased or. decreased within defined limits by change of voltages applied to the various elements; Electrons areattracted to the plate within a certaindefinitelimit determined by the current through the filament and the bias volt: ages upon the grid. Hence, within certain limits, the conductance of the tube may be determined by varying the platevoltage, the initial voltages appliedto the othertube elements remaining unchanged. i 1 v I a In audion tubes the electron flow may be increased or decreased within defined limits by different Voltages applied to the various elements. The electrons are attracted to the platewithin specified limits, as theplate voltage becomes more positive. Hence, within certain' limits theconductance of a tube may be determined by varying only the. plate voltage, while the initialvoltages applied to the other tubeelements remain unchanged. 'By measuring the conductance of the tube under different conditions of plate voltage the worth of a tube can be obtained.

. t'is my object to. maintain the input into the tube or the grid conditions thesame, and to change the applied potentialoi the output or plate circuit, and measuring the plate current with" the two or more applied potentials and subtracting the difference to determine the value ofthe tube.

. grid connected into the plate circuit,

In other words, by having astandard a grid; and

,filament condition and varying the plate condition I can determine the value of the tube.

This application is a division of my copend- .ing application, Ser. No. 585,937, filed January In the present drawings preferred embodiments of this invention are shown. Figure 1 is a form of a circuit diagramioi an alternating current'tube tester, in which the voltage of the plate current is varied byymeans of a potentiometer across the primary coil of a transformer. l a

Figure 2 is a View similar to Figure 1 with the v FigureB is another circuit diagram ofanalternating current tube tester, whi h the primary coil of a transformerfis connected across the source of .an alternating current-and in which there is .one secondary coil; connected to .the filae ment and another connected to the. plate circuit. Figure 4 isaviewsimilar to Figure 3, showing 5 a. floating gridfcrming a part of this secondary circuit connected into the plate circuit. Figure 5. is a view showing an alternating cure. rent tube testerjwith means added thereto for automatically changing the applied potential of the plate circuit, v a

igure 6 is a View similar to Figure 5 but sho ingafloatinggrid. a

I The numeral 1 is used to designate the primary of a transformer, which is connected across the sourceof analtern ating current by means of conductors'l and lla. The secondary 3 of thetransformer is connected by means of conductors 4 to a filament 5 vpfan audion tube 6. Extending from one end ofcthe conductors 4 is a conductor 1, which formsan electrical connection between one of theconductors l and'the intermediate grid 8 of the audion tube; .By means of the conductor 9 the grid this connected to 'the conductor 7.

Extending from the conductor 1 to the con ductor-fiis a conductor i l. The numeral l2 designates the plate of the tube, which has connected thereto asconducto'r i3 extending from the plate to a milliammeter M, which is connected by a conductor E5 to a switch Hi. This switchnormally 30 makes contact witha contact point 58, at one end of a conductor ll, the other end of which con.- ductor is adapted to be adjusted along a potentiometer Hlfor varying the Voltage applied to the tube and through the plate circuit. The potentiometeris connected across the two conductors 2 and 20.. H Extending from the conductor 2a is a conductor 26; which-has on; one end thereof a contact point 2i adapted to be engaged by the switch lii when it is pressed down. t9

When the parts are in the position shown in Figure 1 a certain definite voltageisapplied to the plate current. By shifting the point of contact of the. conductor ll along the potentiometer the voltage may be varied and the resulting variations in the current may be determined by the milliammeter. During these voltage variations the voltages applied to the grid and to the filamentremain constantjand unchanged.

In the form shown in Figure 2 the grid I0 is :connectedto the conductor l3 by means of a conductor 22, which has a resistance 23 therein. In this form a variable voltage is applied to the .plate circuit by shifting the point of contact between the conductor 11 and the potentiometer l9, and pressing the switch Hi to engage the contact point 2|.

In the form shown in Figure 4 the secondary of the transformer is divided into two branches, 3a and 3b, branch 3a being connected to the filament by means of conductors 4, the same as in the other forms. The branch 3b is connected at one end to one of the conductors 4 by a conductor 25, and at its other end by means of a conductor 24 to the contact point 2|. From the contact point N3 of Figure 4 a conductor 26 extends to the secondary 3b. In this form there is a floating grid 21.

With the switch in the position shown in Figures 3 and 4 a certain definite potentiality is applied to the plate l2 and to the plate circuit. This may be varied by varying the connection between the conductor 26 and the coil of the secondary 3b of the transformer. This voltage may also be varied by pressing the switch down so as to contact with the contact point 2 I. When the switch l6 contacts with the point 2| the whole of the voltage of the coil of the secondary 3b is applied to the plate circuit. The voltage may be varied from the whole voltage of this coil to any definite determined part thereof. The variations in the plate currents, due to the variations in the voltages of the plate circuit, are determined by the milliammeter M.

In the forms shown in Figures 5 and 6 there is an automatic means for varying the voltage through the plate circuit. In this form the transformer has its usual two coils I and 3. The secondary is connected to the filament and the grid, as in the form shown in Figure 1, with the exception that in Figure 6 there is a floating grid. In Figure 5 the conductor 28 extends from the conductor 2 of the primary coil of the transformer to the conductors I and 9 so that this conductor 28 is a part of the plate circuit through the tube.

To the conductor 2a of the primary coil of the transformer is, attached one end of a conductor 29, which has on its other end a contact 30. The conductor 2a may have its connection with the primary coil varied so as to produce an increased voltage passing through the plate circuit. Extending from one end of the primary coil of the transformer is a conductor 32, which has extending therefrom a conductor 3i with a contact 35 on the end thereof.

In the forms shown in Figures 5 and 6 the conductor l5 has attached thereto a relay 34 with a shunt 33. 36 is a barrel plunger.

When the parts are in the'position shown in Figure 5 the current will pass from the primary circuit of the transformer, through the conductors 29 and 31, relay 34, conductors l5 and I3, through the plate circuit. The action of the circuit through the relay will cause the arm member 38 to elevate the barrel plunger so that a contact is made between the point 35 and the conductor 31, breaking the contact at the point 30 so that the current will pass through the conductors 32, 3| and 31, and through the plate circuit, thereby increasing the voltage. The resulting current changes, due to the voltage changes, will be read from the milliammeter.

In the form shown in Figure 6 there is a fioating grid 21. In this form the primary of the transformer is connected to the secondary of the transformer by means of a conductor 30. In this form the wire extending from one end of the primary of the transformer has thereon a contact 40. Extending from the conductor 2a of the primary of the transformer is a conductor 39, which has on one end a contact 4 l In the position the parts occupy as shown in Figure 6 the current will pass through the conductor 39, relay 34, conductors l5 and I3, through the plate circuit. Through the operation of the relay 34 the contact at the point 4| is broken. The barrel plunger 36 is elevated so'that a contact is formed between the contact member 42 and the contact point 40. The current now passes through the conductor 39, through the relay 34, conductors l5 and I3, through the tube plate circuit.

By the arrangement shown in Figures 5 and 6, a greater voltage is applied to the plate circuit than that which is passing through the primary of the transformer. This is a means by which the voltage is varied upwardly. The change in the voltage is effected automatically, and the corresponding current changes are indicated by the milliammeter.

It will be understood that it is desired to comprehend within my invention such modifications as come within the scope of my claims and my invention. v

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent, is: v

1. The method of determining the plate resistance of an audion tube, producing an induced secondary current from a primary current, energizing the filament and the grid of said tube by said induced current, applying a definite voltage to the plate circuit from the primary current, automatically varying the voltage applied to the plate circuit of the tube by the voltage applied, and determining the current variation due to the voltage variation.

2. The method of determining the plate resistance of an audion tube which consists in energizing the filament and grid by a current induced by another current, applying a definite voltage from the other current to the plate of the tube, automatically varying the voltage of the plate'by the voltage applied, and measuring the plate current corresponding to each voltage.

3. In an audion tube tester, in combination with an electrical connection between a source of alternating current and an audion tube, means to energize the filament from said source, means to energize the plate circuit, automatic means actuated by the plate voltage to vary the plate voltage, and means to indicate the difference in the plate current condition.

4. In an audion tube tester, in combination with a source of alternating current, means to apply to the tube filament and grid from said source a constant voltage, automatic means actuated by the voltage to apply to the tube plate from said source a variable voltage, and means to indicate the difference in the plate current con dition.

5. In combination in a testing instrument for audion tubes, an audion tube having a filament, grid and plate, a. source of current having the primary of a transformer therein, a transformer whose secondary is inserted with the filament and grid of said tube, a measuring instrument in circuit with said plate, means of applying varying potentials on said plate comprising a switch and means for insertion upon the operation of said switch a portion of the primary of said transformer in the plate circuit, and an automatic electrically operated means in said plate circuit for actuating said switch.

6. In combination in a testing instrument for audion tubes, an audion tube having a filament, grid and plate, a source of current having the primary of a transformer therein, a transformer whose secondary is inserted with the filament and grid of said tube, a measuring instrument in circuit with said plate, means of applying varying potentials on said plate comprising a switch and means for insertion upon the operation of said switch a portion of the primary of said transformer in the plate circuit, an automatic electricomprises energizing the filament circuit and the grid circuit from a source of constant voltage, impressing upon the plate circuit a definite determined voltage, automatically changing by the impressed voltage the voltage to another definite determined voltage, and indicating the different currents in the plate circuit.

8. The method of testing audion tubes which comprises energizing the filament and the grid circuits from an alternating current source, impressing upon the plate circuit a definite determined alternating voltage, automatically changing the impressed voltage through the action of the impressed voltage, and indicating the magnitude ofthe plate currents.

. RAY L. TRIPLETT. 

